syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.9.923/16704 is trying to acquire lock:
ffff88805c8d1020 (&ni->ni_lock/5){+.+.}-{4:4}, at: ni_lock fs/ntfs3/ntfs_fs.h:1222 [inline]
ffff88805c8d1020 (&ni->ni_lock/5){+.+.}-{4:4}, at: attr_data_get_block+0x1bf/0x2a0 fs/ntfs3/attrib.c:976

but task is already holding lock:
ffff88803e6811b0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:554 [inline]
ffff88803e6811b0 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x1e0/0x4e0 mm/util.c:579

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&mm->mmap_lock){++++}-{4:4}:
       down_read_killable+0xa4/0x220 kernel/locking/rwsem.c:1599
       mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:601
       get_mmap_lock_carefully mm/mmap_lock.c:450 [inline]
       lock_mm_and_find_vma+0x2d6/0x340 mm/mmap_lock.c:501
       do_user_addr_fault+0x341/0x1340 arch/x86/mm/fault.c:1366
       handle_page_fault arch/x86/mm/fault.c:1483 [inline]
       exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1536
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
       filldir+0x2bd/0x630 fs/readdir.c:-1
       dir_emit include/linux/fs.h:3587 [inline]
       ntfs_dir_emit fs/ntfs3/dir.c:346 [inline]
       ntfs_read_hdr+0x8a4/0xc10 fs/ntfs3/dir.c:387
       ntfs_readdir+0x9ea/0xec0 fs/ntfs3/dir.c:547
       iterate_dir+0x2f1/0x4e0 fs/readdir.c:110
       __do_sys_getdents fs/readdir.c:319 [inline]
       __se_sys_getdents+0xf1/0x270 fs/readdir.c:304
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&ni->ni_lock/5){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x1520/0x2ce0 kernel/locking/lockdep.c:5237
       lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
       mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
       ni_lock fs/ntfs3/ntfs_fs.h:1222 [inline]
       attr_data_get_block+0x1bf/0x2a0 fs/ntfs3/attrib.c:976
       ntfs_file_mmap_prepare+0x5b3/0xa20 fs/ntfs3/file.c:430
       vfs_mmap_prepare include/linux/fs.h:2071 [inline]
       call_mmap_prepare mm/vma.c:2672 [inline]
       __mmap_region mm/vma.c:2758 [inline]
       mmap_region+0xe78/0x2310 mm/vma.c:2860
       do_mmap+0xc1e/0x10b0 mm/mmap.c:560
       vm_mmap_pgoff+0x275/0x4e0 mm/util.c:581
       ksys_mmap_pgoff+0x4a6/0x720 mm/mmap.c:606
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&mm->mmap_lock);
                               lock(&ni->ni_lock/5);
                               lock(&mm->mmap_lock);
  lock(&ni->ni_lock/5);

 *** DEADLOCK ***

1 lock held by syz.9.923/16704:
 #0: ffff88803e6811b0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:554 [inline]
 #0: ffff88803e6811b0 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x1e0/0x4e0 mm/util.c:579

stack backtrace:
CPU: 0 UID: 0 PID: 16704 Comm: syz.9.923 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043
 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x1520/0x2ce0 kernel/locking/lockdep.c:5237
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
 mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
 ni_lock fs/ntfs3/ntfs_fs.h:1222 [inline]
 attr_data_get_block+0x1bf/0x2a0 fs/ntfs3/attrib.c:976
 ntfs_file_mmap_prepare+0x5b3/0xa20 fs/ntfs3/file.c:430
 vfs_mmap_prepare include/linux/fs.h:2071 [inline]
 call_mmap_prepare mm/vma.c:2672 [inline]
 __mmap_region mm/vma.c:2758 [inline]
 mmap_region+0xe78/0x2310 mm/vma.c:2860
 do_mmap+0xc1e/0x10b0 mm/mmap.c:560
 vm_mmap_pgoff+0x275/0x4e0 mm/util.c:581
 ksys_mmap_pgoff+0x4a6/0x720 mm/mmap.c:606
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff68dbbde59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff68bdf5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007ff68de46090 RCX: 00007ff68dbbde59
RDX: 0000000000000002 RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007ff68dc53e6f R08: 0000000000000006 R09: 0000000000000000
R10: 0000000000028011 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff68de46128 R14: 00007ff68de46090 R15: 00007ffe55b8da08
 </TASK>